The group said that film producers had called a moratorium on production late Wednesday and that filming would not resume until all of Bay's partners are notified and tested.

The incident comes amid continued opposition on the part of many companies that produce adult films to a recently enacted law in Los Angeles County that requires porn actors to use condoms while filming.

The multibillion-dollar adult film industry is centered in the San Fernando Valley area of Los Angeles.

Adult film stars talk about how the industry is changing

Adult performers talk about the changing face of pornography at the AVN Awards.

Michael Weinstein, head of the Los Angeles-based AIDS Healthcare Foundation and a backer of the condom law, said he suspects that Bay contracted the virus on a set.

The actress had tested negative for HIV last month, but tested positive this month, he said. It appears that condoms were not used in one film she worked on between the tests, Weinstein said.

"It's a tragedy for her," Weinstein said. "Obviously, she was infected by someone."

The industry group said there was "no evidence whatsoever" that Bay was infected on a set or that others were exposed to the virus while performing sex scenes with her.

Bay said she planned to cooperate with public health officials as they try to track down her sex partners to find out who might have infected her, and whether she infected anyone.

"As difficult as this news is for me today, I am hopeful that no other performers have been affected," Bay said in a statement. "I plan on doing everything possible to assist the medical professionals and my fellow performers."